The aerodynamic performance of aircrafts, wind turbines, rotor blades and other structures operating at temperatures below 0° C., are severely compromised by the adhesion of ice to their surfaces. The continuous accumulation of ice in aircraft surfaces is known to result in the disruption of the airflow with an increase in drag forces and high losses of energy due to mass-imbalance in the structures. Current efforts to reduce and mitigate the ice formation in aircraft surfaces include: dispersion of chemicals; mechanical removal; and electrical heating of surfaces. Electrical heating systems have proven suitable as deicing systems due to the facile induction of heat to promote continuous removal of ice. However, the metals and alloys for current-induced heating elements result in high power consumption.
Recent studies have focused on use of 1D and 2D carbon-based conductive nanoparticles to develop efficient deicing systems. Due to their lightweight, superior electrical and thermal performance these conductive particles have benefits over conventional metal-based systems. The effectiveness of such systems depends on the intrinsic electrical and thermal conductivity of the filler, as well as the nature of the conductive component. For instance, Wang et al. ACS Applied materials and interfaces, 2016, 8, 14169-73 demonstrated the potential of functionalized graphene nanoribbons (FDO/GNR) as an anti-icing and active deicing film. The resulting FDO/GNR film is capable of preventing the formation of ice in surfaces down to −14° C. Deicing of surfaces is achieved by resistive heating of the film in periods of 90 seconds by implementing power densities of ˜0.2 W·cm−2. However, removal of water remnants in the surface requires the introduction of a lubricating liquid.
Despite success for the deicing of surfaces, performance relies strongly on the distribution of conductive particles in their matrix/surface. Therefore, high concentrations of conductive fillers are required to form a complete conductive network and these particles are limited by their tendency to form agglomerates rather than homogeneous dispersions. Such behavior is attributed to strong π-π interactions between nanoparticles. There appears to be the possibility of superior behavior with more hydrophobic matrixes.
Composites comprising silicone, a low surface energy, hydrophobic material, and graphene have been prepared, for example, Verdejo et al. J. Mat. Chem., 2008, 18, 2221-6, but the process involves infusion of silicone foam with functionalized graphene sheets from suspension. The graphene sheets were of particle size 74 microns into an open-cell silicone foam to form silicone foams with up to 0.25 wt %) graphene sheet infusion and thermal conductivities as high as 0.0748 W/mK, about a 50-fold increase over that of the silicone foam. These foams were considered useful for catalysts, filtration media, and for undisclosed applications in biomedical science. Higher thermal conductivities would be desirable for use in deicing.